The ripe fruit of Capsicum species are a well-known, important source of a variety of carotenoids, including oxygenated carotene derivatives, commonly referred to as xanthophylls. Capsicum species contain capsanthin, capsorubin, cryptocapsin, zeaxanthin, lutein, and other carotenoids that have substantial nutritional and medical value. Epidemiological studies have shown that frequent and regular consumption of carotenoids reduces risks of chronic disorders, such as cardiovascular diseases [Kohlmeier et al. (1995)] or cancer [Murakoshi et al., (1992); Levy et al. (1995); Tanaka et al., 1994) Ito et al. (2005), Connor et al. (2004), and Rock et al. (2005)]. Carotenoids may also function as antioxidants in disease prevention. Both zeaxanthin and lutein are reported to possess strong anti-tumor properties [Packer et al. (1999)]. Epidemiologic studies suggest that the antioxidant potential of dietary carotenoids may protect against the oxidative damage that can result in inflammation. A modest increase in dietary carotenoid intake is associated with a reduced risk of developing inflammatory disorders such as rheumatoid arthritis [Pattison, et al. (2005)].
A higher dietary intake of carotenoids is also associated with a lower risk for AMD (Age-related Macular Degeneration) occurring in older adults. Hereditary forms with an early onset include Stargardts, Best's Disease and progressive Cone Dystrophy. Hereditary retinal degenerations that attack the whole of the retina tend to be more severe. The most common types of these diseases are Retinitis Pigmentosa, Choroideremia, Ushers Syndrome and diabetic retinopathy. Individuals consuming the highest levels of carotenoids exhibit a 43% (statistically significant) lower risk for AMD [Seddon et al., (1994). The specific carotenoids, zeaxanthin and lutein, are most strongly associated with a reduced risk for AMD. Zeaxanthin and lutein are the sole xanthophyll pigments found in the retina and concentrated in the macula. Excellent reviews of the role of carotenoids in the macula are found in Davies, et al., 2004, Stahl et al. (2005), Stringham et al. (2005), Ahmed et al. (2005), Stahl (2005), Beatty et al. (2004), Davies (2004), and Alves-Rodrigues (2004).
There is a strong association between higher consumption of dark green vegetables, which contain xanthophylls, including zeaxanthin and lutein, and a decreased risk for light-induced oxidative eye damage, such as cataract formation, see Brown et al. (1999) and Ribaya-Mercado (2004). Although dark green vegetables are an excellent dietary source of zeaxanthin and lutein, the isolation and purification of these compounds in large quantities from green vegetables is time-consuming and costly. Twenty-five grams of a fresh, dark green vegetable such as kale theoretically provide 10 mg of lutein. (Khachik et al. 1995). Corn, one of the highest plant sources of zeaxanthin, contains 0.528 mg of zeaxanthin per 100 grams of corn (Lutein and Zeaxanthin Scientific Review, Roche Vitamins Technical Publication HHN-1382/0800). It would require 1.9 kg of corn or 0.623 kg of peppers to provide 10 mg of zeaxanthin from these sources.
Therefore, a highly concentrated source of natural zeaxanthin is needed for the manufacture of dietary supplements and functional foods. Moreover, zeaxanthin is an important ingredient to add color to foods and as an additive in animal feeds to color poultry skin, egg yolks, fish flesh and the like. A natural source of zeaxanthin that can be used in foods is preferred and/or regulated over a synthetic product in these applications.
“GRAS” is an acronym for the phrase Generally Recognized As Safe. Under sections 201(s) and 409 of the Federal Food, Drug, and Cosmetic Act (the Act), any substance that is intentionally added to food is a food additive, that is subject to premarket review and approval by FDA, unless the substance is generally recognized, among qualified experts, as having been adequately shown to be safe under the conditions of its intended use, or unless the use of the substance is otherwise excluded from the definition of a food additive. Regardless of whether the use of a substance is a food additive use or is GRAS, there must be evidence that the substance is safe under the conditions of its intended use. FDA has defined “safe” (21 CFR 170.3(i)) as a reasonable certainty in the minds of competent scientists that the substance is not harmful under its intended conditions of use. The specific data and information that demonstrate safety depend on the characteristics of the substance, the estimated dietary intake, and the population that will consume the substance.
Zeaxanthin derived from natural sources is usually obtained as a mixture of free xanthophyll compounds together with the pigment in the form of mixtures of mono and diesters of fatty acids. The fatty acids generally contain from eight to twenty carbon atoms. Methods for converting these esterified forms of zeaxanthin to a free alcohol form are well known and documented. Methods for preparing esters from the non-esterified form are also known and documented.
Zeaxanthin from natural sources is generally obtained in the form of an all-trans isomer. It is well known that the trans isomer can be converted to cis forms by the application of heat and/or light or by the addition of a catalytic amount of iodine (Zechmeister, 1962; Khachik, et al. 1992; Updike et al., 2003; Englert, et al. 1991 and references therein; Karrer and Jucker, 1950. Zechmeister also discusses isomerization by acid catalysts, contact with active surfaces, via boron trifluoride complexes and bio-stereoisomerization. Given the number of double bonds in the structure, a large number of different cis isomers are possible. Both cis and trans isomers have been detected in the retina.
Zeaxanthin also exists in two enantiomeric and one meso form, namely 3R,3′R; 3S,3′S and 3R,3′S (note 3S,3′R is identical to 3R,3′S). All three stereoisomers have been found in the human retina (U.S. Pat. No. 6,329,432), but the 3R,3′R isomer is dominant. It is difficult to separate these three isomers of zeaxanthin from each other in commercial quantities for human consumption. Therefore, for synthetic production of zeaxanthin, either a chiral process or a chiral separation process is needed in order to purify and produce the 3R,3′R stereoisomer.
Age-related Macular Degeneration (AMD) is the leading cause of blindness for people older than 65 in the United States, and is expected to affect 40 million U.S. residents by the year 2030 [Abel, (2004). Treatments to ameliorate the effects of the disease and methods for preventing the onset of the disease are desperately needed. Since lutein and zeaxanthin play a critical role in the protection of the macula, it is important that people have access to these compounds, either through dietary sources, through supplements, or through so-called functional foods, which foods contain enhanced levels of these nutrients. Numerous epidemiological studies suggest that the typical intake of lutein and zeaxanthin is only in the 1-3 mg/day range, see Brown et al. (1999) and Lyle et al. (1999). Seddon et al. (1994) reported a relationship between the intake of lutein and zeaxanthin at 6 mg per day and a decreased risk of AMD and cataracts. This dietary gap of 3-5 mg per day can be eliminated with the use of supplements.
There is a perceived need in the marketplace for naturally derived zeaxanthin, as opposed to synthetic zeaxanthin, that can serve as a dietary source in the form of a dietary supplement, a food or beverage additive, or a food or beverage colorant. Furthermore, there is a need for zeaxanthin for dietary supplements, food or beverage additives, and food or beverage colorants in biologically available forms.
There is also a need for naturally derived zeaxanthin, as opposed to synthetic zeaxanthin, that can serve as an additive in animal feeds, such as poultry feed, to color flesh and skin, egg yolks and fish flesh. Certain types of poultry feed additives prepared from corn gluten contain a relatively high percentage of zeaxanthin (about 15-30%), when measured as a percentage of total carotenoids. However, the total carotenoid content of these feed additives is very low (only about 100 milligrams of total carotenoids per pound of poultry feed). Another type of poultry feed additive is prepared from marigold extracts. This additive contains roughly 100-200 times as much yellow pigment per pound of additive (i.e., about 10 to 20 grams of lutein and zeaxanthin per pound); however, more than 95% of the yellow pigment in this marigold preparation is lutein, not zeaxanthin. Zeaxanthin comprises only about 2 to 5% of the yellow pigment in this poultry feed additive (U.S. Pat. No. RE 38,009).
Genetics
The accumulation of carotenoids in Capsicum fleshy fruit is well studied, with many known biosynthetic genes cloned, sequenced and functionally characterized on some level. Although the majority of investigations into carotenoid biosynthesis has been carried out in the model system Solanum lycopersicon (tomato), additional work has shown a high level of conservation of these genes among all plant species accumulating carotenoids [Hirschberg (2001)]. Also, certain carotenoids show taxonomic specificity. For example, capsanthin and capsorubin are responsible for the red color seen in ripe pods of Capsicum, and are not seen in any other genus. These two carotenoids are synthesized via the action of capsanthin-capsorubin synthase (Ccs) from antheraxanthin and violaxanthin respectively. In the absence of Ccs, peppers do not accumulate significant amounts of capsanthin or capsorubin and the resulting ripe fruit are orange in color [Bouvier, et al., (1994)].
The dietary supplement marketplace in both the US and in Europe does not accept nutrients that are derived from genetically modified organisms. Therefore, there is a need for a naturally derived zeaxanthin product that is not derived from a genetically modified plant.
Currently, zeaxanthin is available from a number of sources. It is produced synthetically, extracted from plant matter and extracted from bacteria.
Synthetic Zeaxanthin
The all-trans 3R,3R′ zeaxanthin isomer is produced synthetically, and a process for its production is disclosed in U.S. Pat. Nos. 4,952,716 and 5,227,507. Synthetic zeaxanthin is commercially available from DSM, who purchased the technology from Hoffmann-LaRoche. Hoffmann-LaRoche had obtained two patents that describe the chemical synthesis of the 3R,3′R isomer of zeaxanthin; these are U.S. Pat. Nos. 4,952,716 and 5,227,507. Processes disclosed therein require the production and purification of three major intermediates, with yields of approximately 70 to 85% for each intermediate from its precursor. The overall process disclosed in these patents apparently requires a series of 14 reaction steps, which take a minimum of 83 hours (excluding purification), and yield a mixture of reactants and products. The final reaction mixture must then be extensively treated to purify the 3R,3′R isomer of zeaxanthin. Accordingly, the entire process required for both synthesis and purification using this technique makes production on a commercial scale overly difficult, and expensive. The zeaxanthin produced synthetically is currently available only in the non-esterified form. A significant problem with certain synthetically derived carotenoids is elevated levels of residual solvents (used in their synthesis) that typically remain in and contaminate the final product. For example, commercial synthetic beta-carotene was analyzed in our laboratory and shown to contain residual levels of toluene or acetone, of 2000 and 1200 ppm, respectively, depending on the synthetic source. These levels, generally unknown to the public, are undesirable, and are roughly 50 to 100 times higher than levels of residual solvents permitted under 21 CFR §173 for spice extractives containing high levels of carotenoids, such as paprika or carrot oleoresin.
Plant Sources of Zeaxanthin
The public generally prefers to consume compounds that are derived from natural sources as opposed to those that are produced synthetically. Natural sources containing high levels of zeaxanthin currently include certain mutant varieties of marigold flower petals, berries of the genus Lycium and Physalis, and specifically Chinese wolfberries (Lycium chinense). U.S. Pat. No. 6,191,293 discloses that preferred materials containing zeaxanthin “include fruits like oranges, peaches, papayas, prunes, and mangos.” There is no mention in this patent of the genus Capsicum. 
Marigolds
Marigold (Tagetes erecta) petals have a long history as a commercial source of the carotenoid pigment, lutein. Dried marigold flowers contain approximately 1-1.6% carotenoids by weight and lutein esters generally account for 90% of the total carotenoids (Antony et al., 2001). U.S. Pat. No. 6,784,351 discloses a mutant marigold that expresses zeaxanthin at high levels, where zeaxanthin is the dominant carotenoid pigment. Marigold petals, however, are not a recognized food. Although lutein derived from marigolds has been introduced as a food additive through the use of the self-affirmed GRAS (Generally Recognized as Safe) process, it cannot be added to foods if it changes the food's color. This is because lutein is not recognized as an exempt food colorant under 21 CFR §73.
There is another problem associated with pigments isolated from marigolds. Marigolds are often planted around gardens because they naturally produce insecticidal compounds and when planted in proximity to other plants, help shield them from insect predation. One type of these natural insecticides is a group of compounds known as terthiophenes and related compounds. Terthiophenes are potent phototoxic agents that cause light-activated damage to biological systems [Downum et al., (1995); Aranson, et al., (1995)]. These phototoxic compounds can be difficult to separate from marigold-derived zeaxanthin. Analysis of commercially available zeaxanthin (and lutein) from marigold sources demonstrates that such preparations contain measurable levels of phototoxic terthiophenes (see Example 12). Therefore, marigold-derived zeaxanthin is certainly not a preferred form for eye health. α-Terthiophene (also known as α-terthienyl) and other marigold constituents, such as butenylbithiophene and hydroxytremetone have been reported to have sensitizing properties leading to allergic contact dermatitis [Hausen et al, (1995)]. The zeaxanthin-containing extracts of the present Capsicum varieties do not contain these sensitizing or photosensitizing components.
Conversion of Marigold-Derived Lutein to Zeaxanthin
Lutein to zeaxanthin isomerization reactions have been known for more than 40 years. One process disclosed in, U.S. Pat. No. 6,376,722 uses sodium ethoxide, methanol, potassium methoxide, methyl sulfate, and combinations thereof to effect this conversion.
The weaknesses of this approach are 1) that zeaxanthin derived from marigolds is not GRAS for food and 2) that phototoxic compounds derived from marigold are not necessarily removed. Additionally, the extra reaction step is also expensive and lowers the yield of zeaxanthin obtained.
Wolfberries
High concentrations of the dipalmitate ester of zeaxanthin have been isolated from wolfberries (Lycium chinense) which have a history of use in Chinese medicine, Zhou et al., (1999). Since they are not a GRAS food substance, according to 21 CFR 182, the potential use of wolf berries in food systems is limited.
Fruit and Vegetable Crops
Zeaxanthin is found in a wide variety of fruits and vegetables as shown in Table 1 (Lutein and Zeaxanthin Scientific Review, Roche Vitamins Technical Publication HHN-1382/0800). These levels are quite low compared to the concentrations present in the instant invention [about 60,000 micrograms/100 g on a raw (wet) basis].
TABLE 1Concentration of zeaxanthin in commonlyconsumed fruits and vegetables.Tangerine, mandarin142 microgram/100 g0.000142%Kale (cooked)173 microgram/100 g0.000173%Spinach (cooked)179 microgram/100 g0.000179%Lettuce (cos or romaine, raw)187 microgram/100 g0.000187%Collard greens (cooked)266 microgram/100 g0.000266%Turnip greens (cooked)267 microgram/100 g0.000267%Spinach (raw)331 microgram/100 g0.000331%Corn (frozen, cooked)375 microgram/100 g0.000375%Persimmons (Japanese, raw)488 microgram/100 g0.000488%Corn (sweet, yellow, cooked)528 microgram/100 g0.000528%Pepper (orange, raw)1606 microgram/100 g 0.001606%Capsicum 
There are two principle types of Capsicum annuum which have a very low capsaicin content: bell and paprika types. The presence or absence of capsaicin, the pungent principle in peppers, is not critical to this invention, as some paprikas are perceptibly hot.
Three major pigment type classes of paprika-type peppers are discussed, which are herein referred to as reds, oranges, and yellows. Red, orange and yellow fruit of the Capsicum genus are generally good dietary sources of carotenoids. The pepper referred to in Table 1. is a Capsicum. The appearance of a given class is determined by the relative amounts of the pigments in combination with the total pigment concentration. Regardless of the total concentration, and visual appearance, these classes can be differentiated by spectral analysis, and by HPLC. For example, a pod from a red paprika will appear orange if it has a low pigment concentration, but has a visible spectrum and HPLC analysis different from the instant orange paprika exhibiting a high zeaxanthin content. In a red paprika, substantial amounts of the red pigments capsorubin and capsanthin are present. In the orange paprika, a minor amount of these two pigments are present, and a very high concentration of zeaxanthin is present. In yellows, the two red pigments are absent as well as a precursor, violaxanthin. Lutein and other yellow pigments and their precursors are present at significantly higher ratios to zeaxanthin, and total pigment content is much lower as shown by a much lower ASTA value.
Table 2. summarizes the concentration of zeaxanthin and the percentage of zeaxanthin relative to total carotenoids in dried Capsicum fruits which have been reported in the literature. Table 2 shows that the percent zeaxanthin with respect to the total carotenoids in the Capsicum, as well as the weight percent of zeaxanthin as a percent of dry weight of the fruit, are much lower than the surprisingly high amounts of zeaxanthin which is characteristic of the instant invention.
TABLE 2Content and ratios of zeaxanthin in prior art Capsicumvarieties (dry weight).Zeaxanthin asZeaxanthin% of totalas % of drycarotenoidsfruit weightReference9.150.045Matus et al., (1991)3.830.06Almela et al., (1991)2.910.043″4.350.058″2.070.026″4.320.053″2.730.027″4.260.034″8.490.273Deli et al., (1992)0.009Minguez-Mosquera et al., (1993)0.03″16.20.161Deli et al., (1996)17.90.109″20.50.027″4.10.033Almela et al., (1996)3.30.044″14.20.019Topuz et al., (2003)130.013″6.30.081Hornero-Mendez et al., (2002)60.045″8.50.064″8.20.056″70.068″6.90.072″8.40.041″140.135″14.90.165″7.70.074″90.073″8.40.081″8.10.049Deli et al., (1997)17.50.0952Deli et al., (2001)8.80.1145″6.20.0312Minguez-Mosquera et al., (1994)10.90.073″7.20.028Muller, H. (1997)3.10.006Camara et al. (1978)7.90.134Minguez-Mosquera et al (1993)4.60.055Minguez-Mosquera et al (1993)5.20.064Minguez-Mosquera et al (1994)9.20.045Biacs et al. (1993)11.30.103Rahman et al (1980)8.90.023Rahman et al (1980)8.10.02Rahman et al (1980)9.20.02Rahman et al (1980)5.280.024Biacs, P. A. et al., (1994).4.5Deruere, J., etal. (1994).2.3Nys, Y. et al., (2000)2.3Fisher, C. et al., (1987)6.5Nys, Y. et al., (2000)6.5Fisher, C. et al., (1987)3.1Nys, Y. et al., (2000)3.1Fisher, C. and Kocis, J. A. J. Agric.Food Chem. 1987, 35, 55-57.4Nys, Y. et al., (2000)4Fisher, C. et al., (1987)15.670.0201Russo, V. M. et al., (2002)11.270.0397Russo, V. M. et al., (2002)Indeed, this fact has been stated by, Breithaupt et al. (2005), who observed “additionally, oleoresins containing zeaxanthin as sole or even major xanthophyll are not available.” One of the highest amounts or levels of zeaxanthin which has been previously described for Capsicum varieties or cultivars is found in the longum nigrum variety as reported by Deli et al., (1992). This variety contains about 0.273% zeaxanthin in the dried, ripe fruit pod flesh. However, the percent ratio of zeaxanthin to total carotenoids in this longum nigrum variety is only 8.49%. Varieties with somewhat higher ratios of zeaxanthin relative to total carotenoids have been described. The lycospersiciforme rubrum varieties described by Deli et al., (1996), show percent ratios of zeaxanthin to total carotenoids of 16.2%, 17.9% and 20.5%; however, the mass of zeaxanthin present in dried, ripe fruit pod flesh is much lower in these varieties, 0.027%, 0.109% and 0.161% of the total dried ripe fruit pod flesh, respectively.
There are reports in the literature on the analysis of carotenoids in fresh Capsicum fruit. The use of fresh versus dehydrated fruit introduces a complicating factor into estimating the amount of zeaxanthin in the fresh fruit for comparison with that amount found in dried fruit (as reported in Table 2). Breithaupt et al., (2001) have found that an orange pepper (Capsicum annuum L. Grossum Grp.) contains 9234 micrograms of total carotenoids per 100 grams of fresh fruit pod flesh. The results were reported as lutein dimyristate equivalents, and neither the absolute nor relative amounts of zeaxanthin were reported. Most paprika-type peppers have a moisture content of 80-85%. Succulent varieties (e.g. bell peppers) have been reported to contain up to 92% moisture (Banaras et al., 1994). Applying assumptions in this case to skew the results toward high zeaxanthin content, specifically, that this pepper was a bell pepper with 92% moisture, and, unrealistically, that zeaxanthin made up all the carotenoids present, the Capsicum sample in question would contain only 0.12% zeaxanthin. Weller et al., 2003, found 3.03 milligrams of zeaxanthin per 100 grams of a fresh orange pepper (Capsicum annuum L.). Using the previous 92% water content assumption, this calculates to 0.04% zeaxanthin on a dry-weight basis. The ratio of zeaxanthin to total carotenoids reported by Weller et al. for this particular pepper was 44%. These authors also describe a red pepper with 16.75 mg of zeaxanthin per 100 g of fresh fruit. Using the same, unrealistic assumption, that this is a bell pepper with 92% water content, this calculates to a 0.21% zeaxanthin. The ratio of zeaxanthin to total carotenoids for this red pepper is only 15%.
Abellan-Palazon, et al., 2001, reported a paprika cultivar treated with titanium ascorbate to have 0.56% zeaxanthin, however, the percentage of zeaxanthin relative to other carotenoids was only 16.6% for this cultivar. The water content of this fresh pepper was given as 79.9% and this was the factor used for the moisture correction. Abellan-Palazon, et al. also reported that after drying this sample, the mass percent zeaxanthin fell to 0.16% and the percentage of zeaxanthin relative to other carotenoids fell to 8.4%. Sommerburg, et al., 1998, report that orange pepper was the vegetable with the highest amount of zeaxanthin with 37 mole percent. Adjusting for molecular weights, this calculates to ˜37.8% by weight, well below the >50% reported in the instant invention. Sommerburg's data do not allow calculation of the mass percent zeaxanthin in the orange pepper from the mole percent data.
Bacterial Sources of Zeaxanthin
Bacteria provide another source of zeaxanthin as in U.S. Pat. No. RE 38,009, which discloses a method to produce zeaxanthin by a fermentation process with Flavobacterium multivorum (ATCC 55238). Other bacteria have been identified that can express zeaxanthin, and they include microbes from the genus Flavobacter (ATCC 21081, 21588, and 11947). Zeaxanthin from a bacterial source is not GRAS. Furthermore, the safety of extracts from bacteria is not established. No commercial source of bacterially derived zeaxanthin is known to be available.